A doctor has spoken out about the shocking instances of suicide attempts, drug overdoses and self-harm at a Darwin immigration detention centre.

A gentlemen was in a room with the health staff and he stood up and apparently took out a light bulb and chewed it in front of them as a measure of desperation...

Northern Territory doctor

The doctor, who wishes to remain anonymous, has told ABC1's Lateline that at least one person a week is trying to take their own life and many more detainees are on prescription medication for insomnia and depression.

Darwin's Northern Immigration Detention Centre is the temporary home for up to 116 asylum seekers.

The doctor, who has worked at the centre, says there is a communal sense of helplessness among inmates.

"A lot of them say, 'I'm depressed. I can't sleep, I can't eat. I can't find motivation to exercise or learn English or do anything constructive.' But a lot of them in terms of the most severe people have asked me to end their life," he said.

"After six to 12 months, most people have attempted some sort of self-harm, either due to complete loss of hope or because they hold on to the small hope that that might lead to a faster end to their detention."

He says many detainees starve or cut themselves and many attempt hanging or to overdose on drugs.

The drugs most commonly prescribed are for depression, psychosis and insomnia.

"Normally they get one week's supply at a time. If you know other people and you're able to ask, 'Can I have your tablets? Can I have one of your tablets?' In time, you can collect quite a lot," he said.

And he has told of disturbing cases of self harm.

"A gentlemen was in a room with the health staff and he stood up and apparently took out a light bulb and chewed it in front of them as a measure of desperation to show them how upset he was at his continued detention. This the second time he's done this in a month and both times he expected to die as a result of it," he said.

Enormous strain

As many as five detainees a day from Darwin's three detention centres are sent to the Royal Darwin Hospital.

Paul Bauert, from the Australian Medical Association NT, says it is putting enormous strain on medical staff and resources.

"Many of the patients present with some mental health problems. They may be chronic anxiety, depression and many are on anti-depressant medications," he said.

"Some are presenting with psychiatric illness and require admission to our psychiatric ward. Some are presenting with injuries from accidents, some are presenting with injuries from self-harm."

They bear the scars of detention, all of them. Some of them are physical, but most of them are mental scars.

Northern Territory doctor

Dr Bauert says it is a frustrating situation.

"We have a policy which is foisting unfortunate detainees onto us. The other frustration is the fact that once we recognise the mental health issues and once we're able to exclude organic pathology, we are immediately sending these people back to exactly the same lock-up facility," he said.

The doctor who has worked in Darwin's detention centre says it is a situation that is doing untold damage to thousands of people every year.

"Ninety per cent plus are found to be refugees and that's after sometimes two, three years in detention," he said.

"And they bear the scars of detention, all of them. Some of them are physical, but most of them are mental scars."

The Immigration Department has told the ABC: "We try to ensure people remain in detention for as little time as possible and ensure that they are treated humanely and have appropriate access to health and mental health care.

"We have introduced new mental health policies and expanded mental health staffing. We have a psychological support (PSP) which is in operation for all people in detention."

The latest information detailing the severe mental health issues among detainees comes on the eve of a parliamentary report into the nation's immigration detention network.

The inquiry has received more than 3,500 submissions.

Greens Senator Sarah Hanson-Young is deputy chair of the inquiry.

"It is a system that is inherently broken. The Government needs to act and needs to act on the recommendations in this report," she said.